Thats a very good question and the best answer isnt 100% clear to me.
I would say it depends on your goals here.
If you are after true aero growth - as in fuzzy roots rather than the normal smooth hydro roots, then you will want to keep as much of the total root mass up out of the water as much as possible. Once the roots hit the water, they will stay smooth.
Smooth roots isnt BAD by any means. Its just not as good as fuzzy roots. So the more fuzzy roots you can get the better.
Thats not going to be easy. When Ive tried root trimming it did seem to cause at least some extra side growth = more fish bones. It also stopped or at least slowed the downward growth for a few days. Its also possible it slowed the entire plant down at the same time. That kind of thing is hard to tell over a short time period.
On the flip side, DWC roots are not bad. No matter what you do, the roots will eventually make it to the water. Something similar happens in all my grows. The roots get to the bottom of the chamber as some point and start to pile up. They get the most mist down there because all the mist goes down eventually. That means they tend to be wetter and smoother than the ones up top. Your situation will be similar but more dramatic in that my root chamber never has standing water - its all fabric and the excess water just drain right through it.
We are talking small increments here and other things can easily add to or erase any gain fuzzy roots give you.
So far, your roots dont look like really happy aero roots - with one exception. One plant does look like its developing some fuzzy’s and some new shoots from the bottom of the pot. For what ever reason, those roots are a lot happier than the other roots.
I personally am fanatical when it comes to fuzzy roots. Its really the only reason I do aero, so keep that in mind. All of my advice is colored by that personal vice 
Any potential extra yields - note I said potential - would just be a bonus. I have been getting very good yields since changing over to HPA and even more with AAA, but Im not 100% convinced aero is the main or only reason. I think the way I do scrog has a lot to do with it too.
If it was me, I would try trimming the roots and see what happens. Id also try to figure out why that one plant is so much happier than the others. Light leaks or air leaks would be my first guesses. I would also check for slime or rotten roots and treat or prune as needed.
How are your root chamber temps? Hi temps may be a reason for the browning or it could just be too low a mist density on average. Or is that one plant closer to the most powerful mister or the furthest or something else?
